Sebastian Vettel completed a practice clean sweep to again leave his rivals in the shade ahead of tomorrow's United States Grand Prix.

Up until the final minutes it appeared as if McLaren would turn the tables on Red Bull after Vettel and Mark Webber formed a one-two yesterday as Lewis Hamilton and Jenson Button led the way at the top of the timesheet.

Vettel, however, had other ideas as he conjured the fastest lap yet at the Circuit of The Americas as the United States makes its Formula One return this weekend after a five-year absence.

On the occasion of his 100th grand prix, on current evidence Vettel appears poised for another pole position as he initially opened up a full-second gap with a lap time of one minute 36.490secs.

Come the conclusion, Hamilton at least managed to close that gap to 0.258secs, with Williams' Pastor Maldonado again in close attendance as the Venezuelan was half a second adrift.

Ferrari's Fernando Alonso, 10 points adrift of Vettel and needing to finish within 15 or better tomorrow to ensure the championship fight goes down to the wire in Brazil next weekend, was 0.690secs down in fourth.

From second late on, Button plummeted to 10th, finishing 1.048secs behind Vettel, who has in his sights the prospect of becoming only the third driver in F1 history to win three successive titles.

Mercedes' Nico Rosberg, Felipe Massa in his Ferrari, Sauber's Sergio Perez and Nico Hulkenberg for Force India, all managed to get ahead of Button in the dying stages.

Perez's erratic form since being confirmed as Hamilton's replacement, however, continued in the final hour-long session, and he faces the prospect of being handed a penalty by the stewards.

Without a point in his last four races, Perez was yesterday fined for speeding in the pitlane, then reprimanded for blocking Marussia's Timo Glock in first practice.

Twenty minutes into FP3 Perez went for a risky and unnecessary move down the inside of Charles Pic in his Marussia, only to broadside the Frenchman and send them both off track.

If given a third reprimand, having also been warned in the last race in Abu Dhabi for blocking Williams' Bruno Senna, Perez will drop back 10 places tomorrow.

Behind the top 10 were Senna and Mercedes' Michael Schumacher, with Lotus duo Kimi Raikkonen and Romain Grosjean 13th and 17th, whilst Force India's Paul di Resta also continues to struggle as the Scot was 16th.

At the rear were HRT duo Pedro de la Rosa and Narain Karthikeyan with times, both just over seven seconds down, that would be outside the 107% rule in qualifying.

As they have been consistently slow, a repeat in qualifying would lead to them not being allowed to compete in the race.

With HRT in deep financial trouble, with suggestions they will go out of business after the race in Brazil, their cars are understood to be running with old parts and so not qualifying would be of benefit.